The present invention relates to light-emitting diodes and light-emitting diode arrays. The light-emitting diode and the light-emitting diode array of the present invention can be used as a signal source in an optical signal transmission system or a light source in an optical printer. Particularly, the light-emitting diode array of the present invention can be used as a light source in an optical printer in which a solid scan method (a method whereby an image having the same size as the original is formed on a photosensitive body by means of a light-emitting array) is employed.
Usually, a surface emitting diode is used as a light source in an optical printer or an optical signal transmission system. A surface emitting diode is constructed such that a film-like contact is formed on a part of a cap layer formed on tope of a semiconductor film layers forming a light-emitting part, and the surface of an insulating film formed on that part of the surface of the cap layer which is not provided with the contact acts as a light-emitting window.
Such a conventional surface emitting diode has the following drawbacks.
When a drive current is applied to the surface emitting diode for light emission, the drive current density is greatest at semiconductor film layers beneath the contact formed on the cap layer, and the intensity of light emission is at a maximum level in this region.
However, since the greater part of light emitted in the semiconductor film layers beneath the contact is reflected by a film-like contact, optical output cannot be effectively obtained through the light-emitting window, resulting in a relatively low light-production efficiency.